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L.A.B.
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Joined: 20 Nov 2004
Posts: 1848
Location: Norfolk, UK
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 Posted: Sat Jul 05, 2008 6:03 am Post subject: |
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| Yellow_Cad wrote: | | Any thoughts on whether or not the things that I described about this bike including the month and year of manufacture make it a good or not so good Commando to have. |
If you want it, and you are able to buy it at a price you are willing to pay, all the paperwork is in order, and there are no signs of any efforts to obliterate or over-stamp any other numbers, then why not?
You may never find the reason for the odd numbers, although you never know, somebody someday could come up with an answer?
I think I'd still want to check if it had an 80 mm stroke or not, though!  |
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79x100
Joined: 19 May 2006
Posts: 689
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| Posted: Sat Jul 05, 2008 6:53 am Post subject: |
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The 1973 850 brochure includes reference to the short-stroke 750 which was available as an engine unit or as a Roadster. It states "polished aluminium head" and this certainly seems to be the case, looking at the close-up engine picture. Quite why they chose for poorer heat dissipation on a tweaked engine is a bit of a mystery  |
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Yellow_Cad
Joined: 02 Apr 2008
Posts: 151
Location: Sacramento, CA
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| Posted: Sat Jul 05, 2008 6:57 am Post subject: |
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| L.A.B. when you say that the 80mm question could be answered further are you thinking that the number of fins does not answer the lenght of stroke question positively? Is there any way to positively answer the stroke question without tearing down the motor? |
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L.A.B.
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Joined: 20 Nov 2004
Posts: 1848
Location: Norfolk, UK
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| Posted: Sat Jul 05, 2008 7:20 am Post subject: |
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| Yellow_Cad wrote: | | L.A.B. when you say that the 80mm question could be answered further are you thinking that the number of fins does not answer the lenght of stroke question positively? |
That info about the shorter barrel could be wrong, as it was just something in the back of my mind that I thought the barrels were shorter? The barrel number you gave is just the casting number, so would not be conclusive either way.
Looking at the photo of the short stroke 750 on the back of the Norton Twin Restoration book I can't say that the barrel looks any shorter?
Of course that bike could have been a mock-up done for the photo session? As the only visible thing that identifies it as being a 750 is the decal on the sidecover and lack of pinstripes?
| Yellow_Cad wrote: | | Is there any way to positively answer the stroke question without tearing down the motor? |
Measuring with a pencil or rod down the plug hole would probably answer that question as there's a fair difference between 80mm (actually 80.4mm) and 89mm.
79x100 said the short-stroke engine is mentioned in the '73 brochure, and it is also mentioned as an engine option for the John Player Norton in the '74 brochure. The short-stroke engine had steel conrods apparently? And I have a couple of images borrowed from ebay of a pair rods that were advertised as being "Norton Commando Short-Stroke Steel Conrods".
But the chances are this is just an odd numbered 850, -so I don't want to get your hopes up over nothing. |
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debby
Joined: 15 Apr 2004
Posts: 890
Location: Boulder, CO
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| Posted: Sat Jul 05, 2008 11:36 am Post subject: |
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| L.A.B. wrote: |
But the chances are this is just an odd numbered 850, -so I don't want to get your hopes up over nothing. |
That seems the most likely scenario. A friend of mine bought an 850 basket case a while back. The engine numbers had been filed off and restamped 200xxx to match the 1972 750 frame that came with it. He said the stamping looked pretty good and probably would have fooled someone who didn't know anything about Nortons.
Debby |
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Yellow_Cad
Joined: 02 Apr 2008
Posts: 151
Location: Sacramento, CA
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| Posted: Sat Jul 05, 2008 1:26 pm Post subject: |
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| So L.A.B., then should raise approximately 89mm for a stock 850 and 80mm if it is a short stroke; correct? |
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L.A.B.
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Location: Norfolk, UK
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Yellow_Cad
Joined: 02 Apr 2008
Posts: 151
Location: Sacramento, CA
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| Posted: Sun Jul 06, 2008 6:08 pm Post subject: |
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| Where on the bike would the Short Stroke decal go? |
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Yellow_Cad
Joined: 02 Apr 2008
Posts: 151
Location: Sacramento, CA
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| Posted: Sun Jul 06, 2008 10:49 pm Post subject: |
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| One other question: On these short stroke Commandos you are seeing photos of, do they have the 850 style crossover exhaust pipes? |
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79x100
Joined: 19 May 2006
Posts: 689
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| Posted: Mon Jul 07, 2008 8:38 am Post subject: |
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| Yellow_Cad wrote: | | One other question: On these short stroke Commandos you are seeing photos of, do they have the 850 style crossover exhaust pipes? |
No, they don't. I'll post some brochure scans later so you can see the beast.
Although they're scarce, the reason for that seems to be that the racers didn't want them. The long stroke 750 was apparently easier to ride. |
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Yellow_Cad
Joined: 02 Apr 2008
Posts: 151
Location: Sacramento, CA
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| Posted: Mon Jul 07, 2008 9:02 am Post subject: |
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What is the consensus: would a short stroke 850 be a good thing or a bad thing. Kommando thought it would be a good thing. I am going to try and measure the stroke tonight.
Also, it has some type of electronic ignition added (owner still has the stock points and cover). The new cover has a flat face the same diameter as the base of the cover and it all protrudes further than the original points cover. Any ideas as to what type of electronic ignition this would be? The electronic ignition would be at least ten years old if not twenty. |
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79x100
Joined: 19 May 2006
Posts: 689
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| Posted: Mon Jul 07, 2008 9:45 am Post subject: |
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Whether the short-stroke 750 is a good thing or not, depends on your reasons for wanting it. It was sold as a tuned engine (4-S cam etc.) The 750 capacity was fixed because of the then-current restrictions for racing.
It is undoubtedly a stronger engine that the long-stroke 750 (it has through bolts so it shouldn't pull the cylinder flange off). I have heard that it lacked the grunt from low revs that the older engine had and generally wasn't as sweet to ride - It still didn't rev like the Japanese.
Generally, if the seller knows what he has then you'd expect to pay more for rarity (you're up against the collectors) and you will find parts harder to obtain and probably dearer.
If you want a fast Norton and have no artificial capacity limit then a large bore engine based on the 850 is probably a better bet.
The ignition system it has will probably be the Lucas RITA (is it a rather flimsy spun cover ?) There are two versions, the earlier with a finned alloy ignition box was a bit power-hungry, the later less so. It's a good system without the Boyer low-volt problems. I don't know how it compares with the latest state of the art units. It is no longer made but I believe that servicing is available. |
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79x100
Joined: 19 May 2006
Posts: 689
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| Posted: Mon Jul 07, 2008 2:42 pm Post subject: |
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750 Short stroke illustration taken from the late 1973 850 brochure. |
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L.A.B.
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Joined: 20 Nov 2004
Posts: 1848
Location: Norfolk, UK
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| Posted: Mon Jul 07, 2008 2:49 pm Post subject: |
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79x100,
That short-stroke engine looks vaguely familiar?: http://www.nortonmotors.de/ANIL/
And it does seem to have all nine barrel fins ! |
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79x100
Joined: 19 May 2006
Posts: 689
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| Posted: Mon Jul 07, 2008 2:57 pm Post subject: |
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Well I never !  Well spotted that man ! That's it for sure
I had been unsuccesfully trying the count the fins in the brochure picture.
The Roadster picture is the same as on Roy Bacon's book and would seem to suggest that the 'Short-stroke' decal might just be a figment of somebody in Rugeley's fertile imagination ! |
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Norton Commando Forum by Corporate Pages Web hosting using phpbb
The Unapproachable Norton Commando
At the end of 1967 the Norton Commando was announced.
The Norton Commando was greeted with a certain amount of scepticism because on first sight the commando appeared to comprise of the old Norton Dominator twin cylinder engine mounted at an inclined angle in a set of new cylinder parts.
It was not realized that the new Norton Commando Isolastic method of engine suspension damped out all engine vibration and produced a machine which had uncanny smoothness for a vertical twin. In due course the critics were silenced and the Norton Commando had the distinction of being regarded as the first of todays so called superbikes. There can be little doubt that the original design concept of the Norton Commando has proved correct, since comparatively few modifications of any real consequence have been made since production commenced during 1968.
Now nearly 40 years later Norton Commando riders like us are a breed of our own, and as far as we are concerned its still more fun to go for a blat on the old Norton Commando, and fast. As a Norton Commando owner and enthusiast, my goal here is to promote and give credit to those who keep the Norton name going.
It is more deserving to give credit to the Commando itself, for after all these years it continues to be respected. The original Commando designers like John Favill are those who deserve the credit for developing this incredible motorcycle.
The Norton Commando Roadster and Interstate of the late seventies, never died. Although the Norton Villiers factory dispersed the tradition lived on. Today Kenny Dreer in the USA is developing the new 952 CC Norton. What a great looking bike this is, and its engineering is still based on the original layout. It will be interesting to see how the new 952CC Norton does in todays tough motorcycle market. One thing is for sure, I would own one if I could afford it.
